Author: Guido
Date: 15:15:33 04/08/03
Go up one level in this thread
On April 08, 2003 at 02:57:42, Tony Werten wrote: >On April 07, 2003 at 14:28:55, Dieter Buerssner wrote: > >>On April 06, 2003 at 16:09:02, Tony Werten wrote: >> >>>For simple EGTB: >>> >>>After placing the white king, there are only 63 squares left, after placing the >>>white king there are only 62 squares left. So the index would be calculated >>>((((SQWK*64)+SQBK)*63)+SQWR) >>> >>>SQBK (square black king ) would be adjusted as follows: if SQBK<SQWK then >>>dec(SQBK) >>>SQWR would be adjusted: if SQWR<SQWK then dec(SQWR); if SQWR<SQBK then dec(SQWR) >>> >>>That's the trick that saves space (well, to start with) Of course it has 1 nasty >>>side effect: You can go from a position to an index, but it's quite impossible >>>to get the position back from an index. >> >>I think it is easy. > >No it's not. The fact that it works in my simplified example doesn't mean >anything, since nobody uses this. I use this in my EGTBs and it is OK also in a not simplified example. I use tables for Kings and for 2 identical men; obviously I need of other tables for each case if I want to go from a position to index and viceversa. For 3 or more identical men I use mathematics for both the transformations. In my opinion the difficulty of the inverse process in Nalimov EGTBs depends on the fact that, in order to reduce the dimensions of the tablebases, positions where there is a check, with the man close to the opponent king, are eliminated from the file. Surely Bob or Eugene can say a final word on this problem. Ciao Guido
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.